Affiliations: Department of Physics, University of Milan, via Celoria 16, 20133 Milano, Italy. E-mail: m.sacerdoti@tiscali.it
Abstract: The speech reviews the Cern experiments AEgIS, ALPHA, ATRAP and ASACUSA for anti-hydrogen production and measure of its characteristics. They all use the Antiproton Decelerator at Cern. AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) is a collaboration of physicists from Cern, France, Italy, Uk, Germany, Switzerland, Russia, Czech Republic, Norway, Qatar. The primary scientific goal of the AEgIS experiment is the direct measurement of the Earth's gravitational acceleration g on antihydrogen. In the first phase of the experiment, a gravity measurement with 1% precision will be carried out by sending an antihydrogen beam through a classical Moire deflectometer coupled to a position sensitive detector. This will represent the first direct measurement of a gravitational effect on an antimatter system. ALPHA is an international collaboration based at CERN, and whose aim is stable trapping of antihydrogen atoms, the antimatter counterpart of the simplest atom, hydrogen. By precise comparisons of hydrogen and antihydrogen, the experiment hopes to study fundamental symmetries between matter and antimatter. It is a collaboration of physicists from Cern, Denmark, Usa, Canada, UK, Israel, Japan, Brazil, Sweden. Alpha has successfully trapped antihydrogen atoms for at least 1000 seconds. ATRAP is an antimatter experiment at Cern whose long term goal is the precise laser or microwave spectroscopy of trapped antihydrogen to make the most stringent lepton and baryon CPT tests. It is a collaboration of physicists from Usa, Germany, Uk. ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) is an antimatter experiment studying: laser and microwave precision spectroscopy of antiprotonic helium atoms (i.e., antiproton+electron+helium nucleus) for testing the CPT (matter-antimatter) symmetry, and contributing to the fundamental physical constants, antihydrogen ground-state hyperfine splitting measurement, for testing the CPT symmetry, atomic and nuclear collision cross sections at extremely low energies. It is a collaboration of physicists from Cern, Austria, Denmark, Germany, Hungary, Italy, Japan, Uk, Northern Ireland.
